Liquid crystal panels have been widely used as display panels for displaying images in display devices of electronic devices such as handheld terminals (for example, smartphones and tablet computers). Such a display device includes the liquid crystal panel and a backlight device (a lighting device) that supplies light to the liquid crystal panel.
An example of the backlight device is described in Patent Document 1 and includes a light guide plate made of transparent plate member, and a light source (for example, LEDs) that is arranged opposite an edge surface of the light guide plate. Such a device is a backlight device of an edge light type (or a side light type). Light emitted by the light source of the backlight device enters the light guide plate through an edge surface of the light guide plate opposite the light source (hereinafter, a light entrance surface). The light travels within the light guide plate and exits the light guide plate through a front-side plate surface (hereinafter, a light exit surface) in a form of planar light. Such an edge light-type backlight device can be reduced in thickness compared to other type of backlight device (for example, a direct-type backlight device). Therefore, the edge light-type backlight devices are preferably used in display devices that highly require reduction in thickness, such as the handheld terminals.
In the configuration of Patent Document 1, the light guide plate is arranged inside a frame-shaped mold (a frame).